What is meant by "so it says something that" in this sentence?

I read this in Word by Word by Kory Stamper:

Don’t think that Gove was a windbag: he was a New Englander and valued sparse efficiency in all things (including lexicography). So it says something that the memos are so long.

Does the latter sentence's construction have some idiomatic significance because it in itself doesn't seem to make much sense? And what does "sparse efficiency" mean in this context? Does it have something to do with New England being sparsely populated? But I'm not getting the "efficiency" part.

Solution 1:

The expression "it says something" here means "it is significant". My father rarely uses strong language, so it says something that he called the Prime Minister "a lying bastard". Because Gove valued sparse efficiency (he preferred economy in all things) it is significant that his memos in this case were long. It is said by some that New Englanders are famously taciturn.

Sparse and efficiency have their normal dictionary meanings:

sparse

adjective ​

small in numbers or amount, often spread over a large area

Sparse (Cambridge Dictionary)

efficiency

noun

the good use of time and energy in a way that does not waste any

Efficiency (Cambridge Dictionary)